Hello Kristian,

I have know what cause the trigger InitializePostBack event,It is because in client side ,I have an event

function WebGrid1_OnRowSelect(gridId, tblName, rowIndex, rowElm) {

            var grid = ISGetObject("WebGrid1");

            var key = rowElm.keyValue;

            {

                grid.AddInput("key", key);

                grid.SendCustomRequest();

            }

            return true;

        }

and grid.SendCustomRequest() cause to trigger the InitializePostBack event.

 I want that when just mouse click one row ,it trigger InitializePostBack ,this has been realized.But when I selected the checkbox,it also trigger InitializePostBack ,I wonder when choosing checkbox,it should not trigger  InitializePostBack ,can this be realized? please see my attachment.Thank you!